Respect other Optional<T> types

It’d be great if Optional<T> types other than Guava and Java 8 would be accepted by Dagger 2. It’s costly to include all of Guava in an Android app, and using Java 8 APIs aren’t an option for many apps, due to only being available on API 24+.

Happy for another alternative though - we just need working optional/nullable binding functionality.

[gildor]

Dagger could do that, but I don’t think we want a world with Guava’s Optional, Java8’s version, and custom versions

But there are cases when it makes sense: Guava is a big library and it’s doesn’t sound reasonable to include it just because of Optional even if you use ProGuard Java 8 Optional is not available on Android before API level 24 (pre-24 devices is about 70%)

I still like an idea about Optional factory, but maybe an alternative solution Dagger could provide own very simple Optional implementation for such cases as separate artifact or as part of runtime library (something like DaggerOptional or OptionalDependency)

[JakeWharton]

One way would be:

public class AnyClass {
  @dagger.OptionalFactory
  public static <T> com.example.Optional<T> anyName(@Nullable T value) {
    return com.example.Optional.fromNully(value);
  }
}